Mum had an affair when I was 6/7.
Mum and Dad only got married after he knocked her up in uni. They were too young. My dad at that time was very faithful and proper.
Soon after, mum waltzed off with her new fella. Dad didn't take too long finding a replacement even though she was hideous. Mum was going to fight for sole custody of me, but grandma persuaded her not to. Both parents continued to live in the same small town so I divided my time equally between both.
I should have hated my new step-dad for breaking up the family, but even though he was a bit of a prick, I got on well with him. It was the new step-mother who was the real problem. I didn't realise it at the time, but she screwed up my personality big time.
Although I describe then as step-dad and step-mum, neither of these relationships turned into marriage and both fizzled out after about 10 years. It was at this time that dad had a midlife crisis and started banging everything that moved. He was right horny old bastard. He even did step-mum's best friend and ruined that relationship.
Mum eventually married a nice bloke and were together nearly 18 years but that has now come to an end. I shudder to think what she will do next. It genuinely scares me.
After getting the sexual frustration out of his system, dad is now hopefully set for life with his current wife.
No matter how you look at it, it was my birth that screwed up both my parents' lives! The moral of the story is to use a condom. Saves you an awful lot of grief.